Seller claims it was attached to shuttle airframe and thermal tiles attached to it, and from Charles Bell.

Robert Pearlman

I have a similar part in my collection —

This segment of Inconel-covered cerachrome insulation once was bolted to a flange on a reinforced carbon-carbon (RCC) component of the shuttle's leading edge structure and was attached to an aluminum wing spar. It protected the metallic fittings and spar from the heat radiated during reentry from the inside surface of the RCC wing panels.

You can see where pieces like this fit in these photos: 1 | 2 | 3 | 4 | 5

garymilgrom

In my opinion these are not that rare, you see them in auctions frequently, and I think the price on this is too high. About half might be right.